FAIRFIELD — The downtown branch of TD Bank was robbed at gunpoint Sunday afternoon by a thief wearing a black ski mask who demanded $100 bills.

The bank at 1643 Post Road was operating on limited Sunday hours when it was robbed about 3 p.m., the scheduled closing time, police said.

The robber confronted the manager, who was near the bank's back door, pulled out a dark semi-automatic pistol, and ordered her to the teller area. There, he put a black bag on the counter and told the manager to fill it with $100 bills. The teller said she didn't have any, and the suspect apparently said, "Come, on, help me out." The manager than put an unknown amount of cash into the bag, police said, and he out the back door.

There no injuries, police said.

The suspect is described as a black man, in his teens or early 20s, about 5 feet, 10 inches tall, with a slender build. He was wearing a dark ski mask, a green hooded sweatshirt, long, dark, possibly blue pajama-like pants with the Polo logo and purple or gray sneakers with a white stripe.

No vehicle was seen when the suspect made his escape.

Located near Interstate 95's Exit/Entrance 21 ramps, the bank has been targeted by robbers several times over recent years. Last Oct. 25, two men robbed the bank, forcing employees into the bank's safe while they made off with money. It has also been robbed in 2008, 2006 and 2005.

Anyone with information about the latest incident should contact police Detective Peter Bravo at pbravo@town.fairfield.ct.us; Detective Alex Fucci at afucci@town.fairfield.ct.us, or by calling 203-254-4840. Anonymous tips can also be texted to 274637.